unique_identifier.h

/*********************************************************************************************************************************************/
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/*  Copyright (c) SILVERCODERS Ltd, http://silvercoders.com                                                                                  */
/*  Project homepage: https://github.com/docwire/docwire                                                                                     */
/*                                                                                                                                           */
/*  SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-DocWire-Commercial                                                                  */
/*********************************************************************************************************************************************/
 
#ifndef DOCWIRE_UNIQUE_IDENTIFIER_H
#define DOCWIRE_UNIQUE_IDENTIFIER_H
 
#include "core_export.h"
#include <atomic>
#include <compare>
#include <functional>
 
namespace docwire
{
 
class DOCWIRE_CORE_EXPORT unique_identifier
{
public:
    unique_identifier() : m_id(m_counter++) {}
 
    unique_identifier(const unique_identifier&) = default;
 
    unique_identifier& operator=(const unique_identifier&) = default;
 
    std::strong_ordering operator<=>(const unique_identifier& other) const { return m_id <=> other.m_id; }
 
    bool operator==(const unique_identifier& other) const = default;
 
private:
    static std::atomic<size_t> m_counter; 
    size_t m_id;                          
 
    friend struct std::hash<unique_identifier>;
};
 
} // namespace docwire
 
namespace std {
template<>
struct hash<docwire::unique_identifier> {
    size_t operator()(const docwire::unique_identifier& id) const {
        return std::hash<size_t>{}(id.m_id);
    }
};
} // namespace std
 
#endif // DOCWIRE_UNIQUE_IDENTIFIER_H